Baffle waste treatment tank baffle waste treatment tank

ABSTRACT

A waste treatment tank has a single baffle dividing an enclosure into a lower aeration compartment and an upper clarification compartment. A blower supplies air to both an aeration air system and a floating waste recycle system. The baffle has openings along its top and bottom permitting controlled communication between aeration and clarification compartments. The aeration air system operates so as to create a circulatory effect in the aeration compartment causing raw sewage to circulate upwardly along a bottom surface of the baffle.

United States Patent [1 1 Ziegler BAFFLE WASTE TREATMENT TANK Leon M.Ziegler, No. 3 McNulty Drive, Manchester, Mo. 63011 Filed: Mar. 17, 1971Appl. No.; 125,278

[76] Inventor:

US. Cl 210/195, 210/221, 210/525 lntQCl. C02c l/l2 Field of Search210/7, 8, 13-15, 210/60, 194, 196, 197, 205, 207, 208, 220, 221, 248,195, 525

[56] References Cited UNITED STATES PATENTS 4/1962 McGivem 210/2208/1965 Williams..'..... 5/1968 Duf0umet..... 9/1968 McKeown..... 8/1962Boester 210/15 X 1 July 10,1973

2,653,907 9/1953 Griffith ..210/194 3,627,135 12/1971 Goodman 210/221 XPrimary Examiner-Samih N. Zaharna Assistant Examiner-Thomas G. WyseAtt0rneyPolster & Polster [57] ABSTRACT 10 Claims, 2 Drawing Figures IPATENIEHJUUOISI'S 3.744537 SHEEIZBFZ QTTORIUEY5 RAFFLE WASTE TREATMENTTANK BACKGROUND OF THE INVENTION This invention relates to apparatus fortreating waste products and in particular to a waste treatment tankconstruction adaptable to domestic use.

Aeration process treatment tanks are well known in the art and theirbasic operational processes are given in the U.S. Pat. to Weis, No.3,161,590 and Kibbee, No. 3,195,727. In general, treatment tanks basedon an aeration process have two tank sections, commonly referred to asaeration and clarification respectively. Raw sewage is introduced intothe aeration tank where it is mixed with air forced into the tank by ablower. The air aids the multiplication of bacteria which convert theraw sewage into a decomposed mixture. As the sewage breaks apart, it isfree to enter the clarification tank.

There, the sewage can be mixed with additional chemicals which render itless offensive and permit its disposal.

Prior art treatment tanks define their aeration and clarification tanksections by baffle systems. It is common to have intercommunicationbetween the sections. Consequently, it is not uncommon to havenondecomposed sewage solids enter the clarification tank section wherethey are responsible for several common tank failures. Non-decomposedsewage solids tend to settle or to rise in the clarification tanksection. Solid sewage entering the clarification tank section with manyair bubbles attached to it, or when the solids are buoyant, will rise,while heavier solids, or those with fewer attached bubbles, settle.Since communication between tank sections commonly is along the bottomwall of the tank, settling sewage solids can'block the communicationpassage, rendering the tank inoperable. On the other hand, rising sewagesolids can block the tank outlet, with inoperability again the result,or they can be discharged, which is undesirable.

Prior art tanks dealt with the settling sewage by developing elaboratebaffle systems which tend to reintroduce settled solids into theaeration tank sections. Rising solids also are reintroduced in theaeration tank section by complicated feedback structures. The Weis andKibbee patents are illustrative. While these prior art tanks accomplishtheir intended purposes, their 9 complex baffles and feedback structuresare oftentimes subject to the very solid sewage blockage they wereintended to relieve. Even "where they are not subject to blockage, theircomplicated construction means considerable product cost, which limitstheir acceptability in the marketplace, particularly in single familydwelling applications. i I

I have developed a novel tank structure utilizing a single baffle platewhich, in conjunction with judi- SUMMARY OF THE INVENTION In accordancewith this invention, generally stated, a waste treatment tank has abaffle dividing it into an aeration and a clarification section.lntercommunication between sections is provided at both the top and thebottom of the baffle. Air flow is introduced into the tank at the bottomof the baffle in. the aeration section and at the top of the baffle inthe clarification section. Aeration section air flow creates acirculatory mixture flow upwardly along the lower wall surface of thebaffle. Air introduced into the clarification section skims sewagesolids from that section and forces solids into the aeration tanksection. The preferred embodiment utilizes a single air mover source forboth aeration and clarification section air flow.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings,

FIG. 1 is a view in perspective, partly broken away, of the wastetreatment tank of my invention; and

FIG. 2 is a sectional view taken along the line 22 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1,reference numeral 1 indicates an enclosure for a waste treatment tank50. En closure 1 generally is cylindrical, having a curved side wall 6,a bottom wall 5 and a top wall 4..

Side wall 6 has an exterior surface 6 and an interior surface 17. Wall 6has an inlet pipe 2 and an outlet pipe 3 from and through surfaces 16and 17. Conventionally, inlet pipe 2 and outlet pipe 3 are positionedsymmetrically and welded in place, usually with the lowermost part ofoutlet pipe 3 below the inlet height.

Top wall 4, in the preferred embodiment, is circular and removablymounted to side 'wall6 by any convenient method. A pair of tabs 18 areprovided to aid in removal of top wall 4 when such removal is required,as, for example, for tank maintenance. Wall 4 has an outer surface 8 andan inner surface 19. Surface 8 supports air supply means 11 mounted onit. Air supply means 11 is conventional and may include a small motordriven compressor or other common air moving means. Air supply means 11provides forced air to an aeration air duct 12 which is described indetail hereinafter. I

Top wall 4 may have access plates or hinge mounted doors (not shown)through it. These access means permit visual inspection of tank portionsand in particular provide access to a sluice box 15 withoutnecessitating complete removal of top 4.

Sluice box 15 is a four sided, open topped rectangular structure fixedto surface 17 of wall 6. It surrounds a vertical leg of outlet pipe 3and serves several. purposes. Sluice 15 provides a controlled headpressure for outlet pipe 3. It also provides a station within tank whereadditional chemicals may be added to further reduce theoffensive natureof the treated sewage. For example,bagged chemicals'may be suspended insluice 15 when such additional treatment is desired. It should be notedthat the tank of my invention also functions satisfactorily, in mostapplications, by relaying on an.

' aeration process for sewage treatment, without the need of anyadditional chemical process. Sluice 15 is conventional. A front 40 has:a drain 4] from and through it as is best seen in FIG. v2. Drainstructures are old in the art and need be little more than common pipeattached to sluice 15 at any desired liquid bleed off height. Asindicated above, however, rising sewage solids can block the tankoutlet. To reduce the effect of rising sewage solids at the tank outlet,I have designed drain 41 in a T shape, although other designs may be 1utilized. Drain 41 has a plurality of openings 42 along the uppersurface of the T cross member. Drain 41 is mounted to sluice 15 below aliquid discharge level 51. Discharge level 51 is defined as the liquidlevel in tank 50 wherein further sewage input necessarily causesliquid'output at outlet 3. Because openings 42 are in the upper surfaceof drain 41, rising sewage solids flow past the opening height withoutblocking it and may be recycled, as is explained fully hereinafter.While the shape of drain 41 may vary, the placement of openings 42 alongthe upper surface of the drain and the physical location of the drainbelow liquid level 51 enables the tank herein disclosed to be subject tofewer outlet blockage problems than tanks heretofore known in the art.

A baffle 10 is positioned within tank 50 so as to divide that tank intoapproximately equal volumetric compartments delineated as an aerationsection 21 and a clarification section 22. Because of the cylindricalshape of tank 50, baffle 10, in general form, is elliptical. Other tankdesigns may require different conforming baffie shapes. Baffle 10 has anupper surface 23, a lower surface 24, a top edge 25 and abottom edge 26,and side edges 29 and 30. Bottom edge 26 is fixed to tank bottom alongtwo leg portions 27 and 28. Edge 26 is cut away from legs 27 and 28 todefine a series of communicative openings 31, 32, and 33 betweenaeration section 21 and clarification section 22. Sides 29 and 30 abutsurface 17 of wall 6 along the vertical rise of baffle in a frictionfit, and may be spot welded to surface 17 if desired.

Top edge 25 has a skimmer opening 36 in it, which receives a skimmerchute 37. The purpose of skimmer chute 37 is described in detailhereinafter. The depth of opening 36, and consequently the height ofchute 37 is chosen so that communication between aeration section 21 andclarification section 22 exists under certain defined conditions. Chute37 is triangular in sidevelevation, having spaced parallel walls 38 and39 connected by a bottom wall 42. Chute 39 is mounted within opening 36and attached to baffle 10 by any convenient method. I

An air distribution system 12 is operatively connected to air supplymeans 11 by common air conduit means 43, through top 4.- 1n theembodiment illustrated, airdistribution system 12 includes aclarification waste removal air faucet l4 and a plurality of aerationdischarge pipes 13. Faucet l4 and pipes 13 may be conventional piping.If desired, they additionally may be treated to resist corrosion.

Faucet 14 may take a variety of forms. A simple opening in air conduitmeans 43 at its connection with distributor system 12 works well.However, in the operation of my invention, it is important that faucet14-direct a current of air from clarification section 22 to aerationsection 21 through skimmer chute 37.

Aeration discharge pipes 13 extend along lower surface 24 of baffle 10and are attached thereto. Pipes 13 and faucet 14 are suppliedby a singleair source 11 in the embodiment illustrated. Pipes 13 are open ended andare positioned to exhaust air near opening 32, be-

tween aeration section 21 and clarification section 22. The positioningof pipes 13, their functional operation with baffle 10 and the releaseof air near opening 32 are important aspects of my invention.

Aeration compartment 21 has a series of flow directors 34, 35 and 7 init. Directors 34 and 35 are placed near baffle 10, and moreparticularly, near openings 31 and 33. Director 7 is positioned in theaeration compartment, approximately from directors 34 and 35. Eachdirector is substantially rectangular in plan. They are attached to sidewall 6 along their material thickness by any convenient method.Directors 34, 35 and 7 primarily are intended to aid in directing liquidflow in tank 50. Each director performs a secondary function in theoperation of the tank of this invention in that solid matter strikingthe directors tends to break apart.

Raw sewage enters tank 50 through inlet 2. The sewage is a mixture ofwater, waste solids and liquids. Solid matter entering the tank strikesdirector 7 which tends to break up large chunks in the sewage. Unbrokenchunks in the sewage liquid tend to settle toward the bottom of tank 50as they first enter the aeration compartment. Liquid level in the tankrises until it reaches discharge level 51. Decomposition of the sewagebegins immediately as the aerated environment of aeration section 21breeds bacteria.

Air supply 11 forces air through pipes 13 where it is released nearopening 32. Air release at this particular position within tank 50 isimportant. First, the release of air near opening 32 causes the liquidabout openings 31, 32 and 33 to become very turbulent as compared to theliquid near the top of tank 50. Turbulence at the openings preventsaccumulation of any settling solids bout those openings. Second, airrelease at the location shown causes air bubbles to rise to the top oftank 50 along lower surface 24 of baffle 10. This air release creates acirculatory flow in the aeration compartment in the direction indicatedin FIG. 2 which keeps sewage particles in the aeration section incontinual motion and exposed to an oxygen source until they decompose inthe aerobic process of the tank. As the liquid flows across level 51 in'the pattern indicated by the arrows in FIG. 2, it flows against sidewall 6 and is directed downwardly thereby towards bottom 5 of tank 50.The downward direction of the flow repeatedly exposes larger sewagesolids to director 7 until they are reduced to acceptable size. Director7 also functions to stabilize flow direction. That is, director 7prevents the development of any circulatory horizontal plane liquidmovement. The flow passes along bottom 5 and is channeled toward opening32 by directors 34 and 35, away from openings 31 and 33. After passingthe directors, the main stream divides. A portion of the stream is drawnupwardly along surface 24 of baffle 10 by the rising air flow. Thisportion of the stream joins the continually regenerative aeration cyclejust described- A second portion of the stream enters clarificationsection 22 at a relatively high velocity, the high velocity being causedby the channel effect of directors 34 and 35. This stream strikes sidewall 6 and disperses. However, the force of the stream adds to thegeneral turbulence about openings 31, 32 and 33.

Some sewage solid particles entering section 22 have air bubblesattached to them. Solids having a large number of air bubbles attachedto them, or those particles normally buoyant, rise toward the top ofsection 22. Rising sewage solids in prior art tanks are responsible foroutlet blockage. Besides the design of drain 41 described above, I havealleviated the blockage problem by use of faucet 14 and skimmer chute37. Faucet 14 faces, and directs an air current toward, aeration section21 through chute 37, as is best seen in FIG. 1. Faucet 14 is adapted andarranged so as to strike discharge level 51 of section 22 at an edge 54of chute 37. The meeting of air and liquid creates a slight depressionof liquid level 51 at chute 37, which depression acts to draw solidsfloating near upper liquid level 51 towards chute 37. As those solidsdraw near chute 37, they are caught by the air stream of faucet l4 andforced into aeration section 21 for recycling.

Where the sewage solids are notbuoyant, they settle. Settling sewagesolids in prior art tanks tend to fall back and block the openingthrough which they entered the clarification section. The turbulencecreated by the air release near opening 32 and the stream flow intoopening 32 prevent this settling in the tank of my invention.

Rather, the solids are forced toward interior wall 17 of side wall 6along each side of baffle 10. As the settling solids near openings 31and 33 in the clarification section, they are drawn back into aerationsection 21 by the circulatory action of the sewage stream as that streamis channeled by directors 34 and 35.

Settling by sewage solids in section 22 is facilitated by the shape ofthe clarification section, best illustrated in FIG. 2. As there shown,section 22 is substantially V- shaped in cross section. The expandingnature of clarification section 22 reduces the velocity of the enteringliquid stream and the suspended solids are enabled to settle and berecycled.

The tank thus described produces an acceptable, clear discharge andreduces to the point of eliminating tank failures due to sewageblockage. The turbulent nature of the liquid flow at the tank bottomprevents accumulation of solids in that area while simultaneouslyproviding means for reintroducing settling solids into the aeration tanksection. Air faucet 14 provides an uncomplicated solution to risingsewage solids and likewise provides for reintroducing the solids to theaeration section.

Numerous variations, within the scope of the appended claims', willoccur to those skilled in the art in the light of the foregoingdescription and accompanying drawings. For example, the shape of tank 50and baffle 10 may be varied. Although I prefer a cylindrical design,spherical or other geometrical shapes are satisfactory. Likewise, themethod of support baffle 10 can be altered. Air distribution system 12may be modified. Thus, faucet 14 and pipes 13 may be supplied fromseparate sources. Likewise, the design of faucet 14 may be varied.Faucet 14 may comprise addition pipe which releases air near liquidlevel 51 rather than the opening described in the preferred embodiment.Various other materials may be utilized in tank construction. Thus, tank50 may be fiberglass or other structural materials, for example. Certainconventional features may be added or deleted. Some commercialembodiments of my invention eliminate sluice box 15 when additionalchemical treatment of the discharged liquid is unnecessary. Thesevariations are merely illustrative.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

l. A waste treatment tank havingmeans for supplying air for carrying outan aeration process on raw sewage, which comprises;

an enclosure having an inlet for raw sewage and an outlet for removal ofprocess waste therethrough, said enclosure including a bottom wall;

a baffle mounted in said enclosure, having a top wall and a bottom wall,dividing said enclosure angularly into two compartments, saidcompartments comprising a clarification section along said top bafflewall and an aeration section along said bottom baffle wall, said baffleincluding an upper edge, and a lower edge extending along said bot tomwall of said enclosure, said lower edge having at least three, spaced,serially arranged openings in it permitting communication between saidaeration and said clarification sections, two of said openings alongsaid lower baffle edge being placed near said enclosure and the third ofsaid openings being inboard of and spaced from said two openings, saidupper baffle edge having an opening in it, said baffle preventing liquidcommunication between said aeration and said clarification sectionsalong said upper edge of said baffle, except along said upper edgeopening;

an aeration system adapted to supply air from said air.

supply means to said aeration section, arranged and carried by saidbottom baffle wall so as to circulate said sewage upwardly along saidbottom baffle wall;

means for removing solid waste from said clarification section, saidsolid waste removing means comprising an air skimmer adapted to direct acurrent of air through said upper edge opening in said baffle;

a first flow director mounted in said aeration section in front of oneof the outboard ones of said three bottom edge openings, said first flowdirector having a width less than the width of said enclosure bottomwall, adapted to direct flow toward said inboard opening of said lowerbaffle edge, along said enclosure bottom wall; and

a second flow director mounted in said aeration section' in front of theother outboard ones of said three bottom edge openings near saidenclosure, said second flow director having a width less than the widthof said enclosure bottom wall, adapted to direct flow toward saidinboard opening of said lower baffle edge, along said enclosure bottomwall.

2. The waste treatment tank of claim 1 further characterized by a thirdflow director mounted in said aera tion section approximately, from eachof said first and said second flow directors.

3. The waste treatment tank of claim 2 further characterized by aT-shaped drain, the cross of said T-shape having an upper surface withat least one opening therein, said drain being communicatively arrangedbetween said clarification section and said enclosure outlet andpositioned within said enclosure so as to be below the height of saidoutlet.

4. The waste treatment tank of claim 3 wherein said air supply meansprovides air to both of said aeration supply system and said solid wasteremoving means.

5. A waste treatment tank having means for supplying air for carryingout an aeration process on raw sewage, which comprises:

a cylindrical enclosure, said enclosure havinga top wall, a bottom wall,and a side wall, said side wall having an inlet for raw sewage and anoutlet for re moval of process waste extending from and through saidside wall, positioned near said top wall;

5 an elliptical baffle, mounted in said enclosure, having atop wall anda bottom wall dividing said enclosure angularly into two substantiallyequal volumetric compartments, said compartments comprising aclarification section along said top. baffle wall and an aerationsection along said bottom baffle wall, said baffle including an upperedge and a lower edge, said lower edge having at least three spacedopenings in it, at least two of said openings in said lower edge lyingoutboard and on opposite sides of a central opening, said lower edgeopenings permitting communication between said aeration and saidclarification sections, said upper edge having an opening in it, saidbaffle preventing liquid communication between said aeration and saidclarification sections at said upper edge except along said upper edgeopening;

means for removing solid waste from said clarification section, saidsolid waste removing means comprising an air skimmer adapted to direct acurtain of air through said upper edge opening in said baffle;

a first flow director mounted in said aeration section of said enclosurein front of one of said outboard openings, said first flow directorhaving a width less than the width of said enclosure bottom wall,adapted to direct flow toward said central opening in said lower baffleedge;

a second flow director mounted in said aeration section in front of theother of said outboard openings in said bottom edge of said baffle, saidsecond flow director having a width of less than the width of saidenclosure bottom wall, adapted to direct flow toward said centralopening in said lower baffle edge; and

a third flow director mounted in said aeration section approximately 90from each of said first and said second flow directors.

6. A waste treatment tank having means for supply ing air for carryingout an aeration process on raw sewage, which comprises:

aeration and said clarification sections except along said upper edgeopening;

an aeration supply system adapted to supply air from said air supplymeans to said aeration section, arranged and carried by said bottombaffle wall so as to circulate said sewage upwardly along said bottombaffle wall;

a first flow director mounted in said aeration section adapted to directflow toward said central opening in said lower baffle edge and to retardflow into said clarification section through at least one of saidoutboard openings, said first flow director having a width substantiallyless than the width of said bottom wall of said enclosure;

a second flow director mounted in said aeration section of saidenclosure adapted to direct flow toward said central opening in saidlower baffle edge and to retard flow into said clarification sectionthrough at least the other one of said outboard openings, said secondflow director having a width substantially less than the width of saidbottom wall of said enclosure; and

means for removing solid waste from said clarification section, saidsolid waste removing means comprising an air skimmer adapted to direct acurrent of air through said upper edge opening in said baffle.

7. The waste treatment tank of claim 6 wherein said baffle divides saidenclosure into substantially equal volumetric compartments.

8. The waste treatment tank of claim 7 further characterized by aT-shaped drain, the cross of said T having an upper surface with atleast one opening therein, said drain being communicatively arrangedbetween said clarification section and said enclosure outlet andpositioned within said enclosures so as to be below the heigth of saidoutlet.

9. The tank of claim 8 further characterized by a third flow directormounted in said aeration section approximately from each of said firstand said second flow directors.

10. The waste treatment tank of claim 9 wherein each of said flowdirectors are substantially rectangular in plan.

1. A waste treatment tank having means for supplying air for carryingout an aeration process on raw sewage, which comprises: an enclosurehaving an inlet for raw sewage and an outlet for removal of processwaste therethrough, said enclosure including a bottom wall; a bafflemounted in said enclosure, having a top wall and a bottom wall, dividingsaid enclosure angularly into two compartments, said compartmentscomprising a clarification section along said top baffle wall and anaeration section along said bottom baffle wall, said baffle including anupper edge, and a lower edge extending along said bottom wall of saidenclosure, said lower edge having at least three, spaced, seriallyarranged openings in it permitting communication between said aerationand said clarification sections, two of said openings along said lowerbaffle edge being placed near said enclosure and the third of saidopenings being inboard of and spaced from said two openings, said upperbaffle edge having an opening in it, said baffle preventing liquidcommunication between said aeration and said clarification sectionsalong said upper edge of said baffle, except along said upper edgeopening; an aeration system adapted to supply air from said air supplymeans to said aeration section, arranged and carried by said bottombaffle wall so as to circulate said sewage upwardly along said bottombaffle wall; means for removing solid waste from said clarificationsection, said solid waste removing means comprising an air skimmeradapted to direct a current of air through said upper edge opening insaid baffle; a first flow director mounted in said aeration section infront of one of the outboard ones of said three bottom edge openings,said first flow director having a width less than the width of saidenclosure bottom wall, adapted to direct flow toward said inboardopening of said lower baffle edge, aLong said enclosure bottom wall; anda second flow director mounted in said aeration section in front of theother outboard ones of said three bottom edge openings near saidenclosure, said second flow director having a width less than the widthof said enclosure bottom wall, adapted to direct flow toward saidinboard opening of said lower baffle edge, along said enclosure bottomwall.
 2. The waste treatment tank of claim 1 further characterized by athird flow director mounted in said aeration section approximately 90*from each of said first and said second flow directors.
 3. The wastetreatment tank of claim 2 further characterized by a T-shaped drain, thecross of said T-shape having an upper surface with at least one openingtherein, said drain being communicatively arranged between saidclarification section and said enclosure outlet and positioned withinsaid enclosure so as to be below the height of said outlet.
 4. The wastetreatment tank of claim 3 wherein said air supply means provides air toboth of said aeration supply system and said solid waste removing means.5. A waste treatment tank having means for supplying air for carryingout an aeration process on raw sewage, which comprises: a cylindricalenclosure, said enclosure having a top wall, a bottom wall, and a sidewall, said side wall having an inlet for raw sewage and an outlet forremoval of process waste extending from and through said side wall,positioned near said top wall; an elliptical baffle, mounted in saidenclosure, having a top wall and a bottom wall dividing said enclosureangularly into two substantially equal volumetric compartments, saidcompartments comprising a clarification section along said top bafflewall and an aeration section along said bottom baffle wall, said baffleincluding an upper edge and a lower edge, said lower edge having atleast three spaced openings in it, at least two of said openings in saidlower edge lying outboard and on opposite sides of a central opening,said lower edge openings permitting communication between said aerationand said clarification sections, said upper edge having an opening init, said baffle preventing liquid communication between said aerationand said clarification sections at said upper edge except along saidupper edge opening; means for removing solid waste from saidclarification section, said solid waste removing means comprising an airskimmer adapted to direct a curtain of air through said upper edgeopening in said baffle; a first flow director mounted in said aerationsection of said enclosure in front of one of said outboard openings,said first flow director having a width less than the width of saidenclosure bottom wall, adapted to direct flow toward said centralopening in said lower baffle edge; a second flow director mounted insaid aeration section in front of the other of said outboard openings insaid bottom edge of said baffle, said second flow director having awidth of less than the width of said enclosure bottom wall, adapted todirect flow toward said central opening in said lower baffle edge; and athird flow director mounted in said aeration section approximately 90*from each of said first and said second flow directors.
 6. A wastetreatment tank having means for supplying air for carrying out anaeration process on raw sewage, which comprises: an enclosure includinga bottom wall, said enclosure having an inlet for raw sewage and anoutlet for removal of process waste therethrough; a baffle mounted insaid enclosure, having a top wall and a bottom wall, dividing saidenclosure angularly into two compartments, said compartments comprisinga clarification section along said top baffle wall and an aerationsection along said bottom baffle wall, said baffle including an upperedge and a lower edge, said lower edge having at least three spacedopenings along it, at least two of said openings in said lower edgebeing outboard and on opPosite sides of a central opening, said upperedge having an opening in it, said upper edge of said baffle preventingliquid communication between said aeration and said clarificationsections except along said upper edge opening; an aeration supply systemadapted to supply air from said air supply means to said aerationsection, arranged and carried by said bottom baffle wall so as tocirculate said sewage upwardly along said bottom baffle wall; a firstflow director mounted in said aeration section adapted to direct flowtoward said central opening in said lower baffle edge and to retard flowinto said clarification section through at least one of said outboardopenings, said first flow director having a width substantially lessthan the width of said bottom wall of said enclosure; a second flowdirector mounted in said aeration section of said enclosure adapted todirect flow toward said central opening in said lower baffle edge and toretard flow into said clarification section through at least the otherone of said outboard openings, said second flow director having a widthsubstantially less than the width of said bottom wall of said enclosure;and means for removing solid waste from said clarification section, saidsolid waste removing means comprising an air skimmer adapted to direct acurrent of air through said upper edge opening in said baffle.
 7. Thewaste treatment tank of claim 6 wherein said baffle divides saidenclosure into substantially equal volumetric compartments.
 8. The wastetreatment tank of claim 7 further characterized by a T-shaped drain, thecross of said T having an upper surface with at least one openingtherein, said drain being communicatively arranged between saidclarification section and said enclosure outlet and positioned withinsaid enclosures so as to be below the heigth of said outlet.
 9. The tankof claim 8 further characterized by a third flow director mounted insaid aeration section approximately 90* from each of said first and saidsecond flow directors.
 10. The waste treatment tank of claim 9 whereineach of said flow directors are substantially rectangular in plan.